The present invention is directed, in general, to electronics devices and, more specifically, to an electronics device having a conductive trace aligned with a thinned portion of a substrate, a method of manufacture therefor, and a system including the same.
High speed communications continue to present ever-increasing demands for ultra-high frequency electronics. Accordingly, as semiconductor and sub-micron lithography technologies advance, more and more high performance chips have been designed with the intent to meet these demands. Such high performance chips may include ultra-wide bandwidth electro-optic (EO) and electroabsorption (EA) modulators. However, a major bottleneck for large scale commercial production of ultra-high frequency electronic components exists as the ultra-wide bandwidth device packaging technology becomes more and more demanding.
Ultra-wide bandwidth devices employ a planar circuit structure, thereby capitalizing on continued advancements in integrated circuit design and fabrication technology. Integrated circuit dimensions may be on the order of about 0.1 microns to about 10 microns. However, signal sources often arrive at the planar circuit structure via coaxial cable, which may have a diameter between about 0.2 millimeters and about 1 millimeter. The signal source, therefore, requires an electrical connector between the coaxial signal cable and the planar circuit. A coax-to-planar circuit transition is needed to couple the signal to the device circuit. In order to accommodate this transition, bonding pads, circuit bends, and tapered circuit sections are required. However, as the operation bandwidth increases, large coupling loss occurs at certain frequencies due to substrate mode coupling. That is, the input signals couple to the substrate instead of coupling to the desired circuit on the substrate.
Theoretical analysis shows that substrate mode coupling occurs when signal frequency reaches a threshold value. This threshold value is inversely proportional to the substrate thickness. An ultra-wide bandwidth device requires this threshold frequency value to be as high as possible, so that signals having frequencies beneath the threshold value do not couple to the substrate instead of the desired circuit. Therefore, in device design, it is important to push this coupling threshold frequency out of the desired bandwidth of the signal.
Based on the inverse proportionality relationship between the threshold frequency and the substrate thickness, the frequency modes at which signal coupling to the substrate can be eliminated or significantly reduced by decreasing the substrate thickness or by reducing the bonding pads dimensions. For example, an ultra-wide bandwidth lithium niobate modulator requires a substrate thickness less than 0.25 millimeters. However, decreasing substrate thickness or bond pad width has drawbacks in large-scale production. For instance, thin substrates are very difficult to handle and are very fragile, thereby increasing per unit cost and decreasing profitability and component reliability. In addition, small bond pads have large mismatch with coax connectors, demand exacting accuracy and critical tolerances during fabrication and assembly, and increase labor and capital requirements, which also increase costs and decrease profits and component reliability.
Accordingly, what is needed in the art is an electronics device and method of manufacture therefor that avoids the disadvantages associated with the prior art.
To address the above-discussed deficiencies of the prior art, the present invention provides an electronics device, a method of manufacture therefor, and a system including the same. The electronics device includes a substrate that has first and second opposing surfaces and first and second thicknesses, wherein the second thickness is less than the first thickness. The electronics device further includes a conductive trace having an input end and an output end and located over the first surface of the substrate, wherein at least one of the input end or output end is aligned with the second substrate thickness.
The foregoing has outlined preferred and alternative features of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for designing or modifying other structures for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention.